The Multiple-Input Multiple-Output (MIMO) technology is a technology in which multiple transmitting antennas and multiple receiving antennas are respectively used at the transmitting side and the receiving side. With this technology, a transmission signal can be transmitted through multiple antennas at the transmitting side and the receiving side, thereby improving communication quality. Further, space resources can be fully utilized, the Multiple-Input Multiple-Output can be achieved through multiple antennas, and system capacity can be effectively increased without increasing spectrum resources and antenna transmission power.
The non-orthogonal transmission technology is a technology in which a signal is transmitted in a non-orthogonal manner at the transmitting side. For example, each subchannel or subcarrier is no longer allocated to one user, but is shared by multiple users. Multiple users on the same subchannel or subcarrier transmit signals in a non-orthogonal manner. The receiving side demodulates data of the multiple users by an interference cancellation method. The Sparse Code Multiple Access (SCMA) technology is one of non-orthogonal transmission technologies. In the SCMA technology, user data is spread to limited subchannels or subcarriers by the sparse spread spectrum to reduce system complexity.
It is desired to provide a solution combining the MIMO technology with the non-orthogonal transmission technology, to increase the number of data flows that can be independently transmitted in an MIMO system, thereby improving transmission efficiency.